Biochemical and anatomical subcellular studies will be carried out to clarify the neurotransmitter uptake processes of mesenteric arteries of hypertensive rats. Our studies on incorporation of radioactive norepinephrine (3H-NE) into synaptosomal fractions of heart and blood vessels indicated an enhancement in mesenteric arteries of spontaneously hypertensive rats (SHR) and sinoaortic denervated rats (SAD) but a reduction in the veins and atria from the same hypertensive animals, as compared to their respective controls. We wish to determine if biochemical and/or structural alterations occur in membranes of storage vesicles and/or axon terminals of hypertensive animals and whether these changes occur prior to the onset of hypertension in SHR. We will study specific Ne transport across axon terminal membrane and storage vesicular membrane by use of isolated synaptosomes and storage vesicles prepared from mesenteric arteries of SHR and SAD rats. Mesenteric arteries prehypertensive SHR and early postoperative SAD at 3-5 days will also be studied for specific NE uptake across axon terminal membranes and storage vesicular membranes by use of whole blood vessels, isolated synaptosomes and storage vesicles.